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Swapping a quartz Ronda for an automatic: what to check

Replacing a Ronda quartz movement with an automatic is rarely a straight drop-in, because a mechanical calibre differs in height, stem position, hand sizes and dial feet.

Why a quartz-to-automatic swap is not simple

Quartz movements such as the Ronda 515, or the 5030.D used in quartz chronographs, are built to a different footprint from mechanical calibres. They tend to be thinner and use their own stem heights, hand-hole sizes and dial-foot layouts. Dropping in an automatic like an ETA 2824-2 or a Seiko NH35 means the case, dial and hands were all cut for the quartz, not the mechanical, so a like-for-like fit is the exception rather than the rule.

It can be done, but treat it as a rebuild of the fit rather than a simple movement change.

The measurements that will trip you up

Height comes first: an automatic is usually taller than the quartz it replaces, so the case may not close. Then the stem position and height, which almost never coincide between a quartz and an automatic, so the crown will not line up. Then the hand-hole sizes, because quartz and mechanical pinions differ, so your existing hands may not press on. Finally the dial feet, which locate the dial and rarely match across the two types.

Every one of these has to be checked, and more than one usually needs addressing to make the swap work.

What you often need to change

In practice a quartz-to-automatic conversion frequently needs new hands sized to the automatic, a dial modified or re-footed to locate on the new movement, and confirmation that case depth allows for the taller calibre and any date-window shift. None of that is a reason not to do it, but it is a reason to plan the parts before you order the movement.

Compare the exact figures for both movements first, so you know which of these you are taking on.

Check the numbers side by side

Before committing, put the Ronda's dimensions next to the automatic you have in mind and see where they diverge on height, stem and hand sizes. Our per-calibre pages carry those figures for common quartz and automatic movements, so you can judge how much of a conversion the swap really is.

Related

Sources: Ronda technical data · ETA/Sellita/Miyota/Seiko Instruments manufacturer technical sheets